CINCHONA 263 



outer surface is of a dull dark grey or dull brownish colour marked 

 with lighter, whitish patches. The outer layer is rugged, and exhibits 

 shallow, rather broad longitudinal fissures that are frequently of a 

 brownish colour, and hence, even if not deep, are easily seen. Trans- 

 verse cracks mark the bark at distances of 6 to 12 mm. This layer 

 shows in many pieces a decided disposition to exfoliate, the inner 

 portion, which is of a dull yellowish brown colour, bearing impressions 

 corresponding to the cracks of the cork. 



The bark breaks with a shortly fibrous fracture ; the section exhibits 

 a narrow dark brown outer layer (cork) and brown inner portion. 



The taste is distinctly bitter and astringent, the former quality 

 predominating. 



2. G. Ledgeriana. This species, which is consideredby some botanists 

 to be a variety of C. Calisaya, yields a bark that very closely resembles 

 quill calisaya in general appearance and is remarkable for its richness 

 in quinine. On this account the tree is being largely cultivated in 

 Java and also in India in preference to other species ; most of the 

 ' yellow ' bark of commerce is Ledger bark imported from Java. 



Commercial Ledger bark occurs usually in single, sometimes in 

 double, quills about the same size as quill calisaya. The colour in- 

 ternally is a dull tawny brown, often with a reddish tinge ; externally 

 the quills mostly exhibit large light grey or whitish patches of lichen. 



They are marked with longitudinal furrows and transverse cracks, 

 which, however, are usually more numerous and less conspicuous than 

 in quill calisaya ; hence the bark is rougher than quill calisaya. Some 

 pieces bear distinct longitudinal ridges and scattered reddish warts 

 that recall typical red bark (see below), but from this bark they are 

 easily distinguished by their colour and by their taste, which is bitter 

 but not markedly astringent. Sometimes the cork shows a distinct 

 disposition to exfoliate as it does in quill calisaya, but in this feature 

 the bark varies considerably. 



As already observed, Ledger bark bears a close resemblance to quill 

 calisaya ; it is best distinguished by its more numerous and less 

 conspicuous longitudinal fissures and transverse cracks. 



3. G. officinalis. The bark of this species, commercially known as 

 pale cinchona or crown bark, is obtained chiefly from India, although 

 some is imported from South America. It occurs in quills only, 

 and these are much narrower than those of quill calisaya, seldom 

 exceeding 12 mm. in diameter, the bark itself being usually less than 

 1-5 mm. thick. They are frequently inrolled on both margins, so 

 as to form double quills. The outer surface is of a dull brown colour, 

 and often has foliaceous lichens adhering to it. Typical pieces are 

 marked with numerous transverse cracks often less than 6 mm. 

 apart, in addition to which there are numerous less prominent longi- 

 tudinal cracks, all of which, but especially the transverse, tend to 

 impart to the bark a roughness to the touch that is characteristic. 



